Good, Bad of Cold-weather Workouts
From VOA Learning English, this is the Health & Lifestyle report.
In winter, people might lessen their outdoor exercise. The days get dark earlier, and it can be very cold! These conditions can make it harder for some of us to get outdoors for exercise.
However, cold days can be perfect for outdoor workouts!
There are at least three important health benefits to cold-weather workouts.
1. The body works harder in cold weather.
Health experts at the Medical University of South Carolina say the body must make extra energy to keep warm in low temperatures. This means the body is burning more calories and fat.
Your lungs also may work better in cold weather. Researchers at Northern Arizona University in Flagstaff found some interesting results in a study of goats.
Yes, I said "goats."
But still, their results were pretty interesting.
The scientists looked at how cold-weather activity affected goats. They found that "during the three coldest months, the sedentary but cold-exposed goats experienced a 34% increase in maximal oxygen uptake ... and a 29% increase in running speed." When temperatures increased in the spring both oxygen uptake and running speed of the goats decreased.
2. Regular cold-weather exercising may help the immune system.
The winter season is also cold and flu season. Making outdoor exercise a usual part of your workout may help you avoid both colds and the flu. It may strengthen your body's defense system.
The Mayo Foundation for Medical Education and Research found that winter workouts can cut your risk of getting the flu by 20 to 30 percent.
3. Exercising outdoors in cold weather may help your mental health.
Some people who suffer from "winter blues" or Seasonal Affective Disorder, may benefit from going outside to exercise in the fresh air and sunshine.
An outdoor workout increases exposure to sunlight. Sunlight helps the body produce vitamin D. And vitamin D produces hormones that brighten your mood.
Dangers of a cold-weather workout
So, there are several health benefits of exercising outdoors in very cold weather. But there are also dangers.
Frostbite is one of the most common.
Edward Ward is a doctor at Rush University Medical Center. He explains how frostbite happens.
"When the air temperature drops below zero especially factoring wind chill, things freeze. And that includes the fluids that's within your fingers or your toes, nose, ears, anything that's exposed to that wind chill can be affected by frostbite."
Protecting your fingers, toes, ears and nose is very important. Cold winds affect these parts of the body more quickly than other parts.
Christopher Sampson is a doctor with University of Missouri Health Care. He explains that frostbite can happen rapidly -- in less than 30 minutes.
"With frostbite people can start experiencing symptoms pretty rapidly, on average with mild winds and cold temperatures it can occur in as less than 30 minutes, with extreme cases. When it's very, very cold and winds are very, very strong, sometimes frostbite can develop in as little as 5 minutes."
The beginning of frostbite is called "frostnip."
Experts at the Mayo Clinic explain that "with this mild form of frostbite, your skin pales or turns red and feels very cold. Continued exposure leads to prickling and numbness in the affected area. As your skin warms, you may feel pain and tingling. Frostnip doesn't permanently damage the skin."
But, frostbite can. It can even lead to loss of tissue and limbs.
The most serious danger is hypothermia. Hypothermia is when the body temperature has fallen below 35 degrees Celsius or about 95 degrees Fahrenheit. This happens when your body can not produce enough energy to keep the body warm enough.
Hypothermia can kill you. There are several signs to watch for before it is too late.
difficulty in movement
difficulty in thinking
cold feet and hands
Falling on ice
However, Dr. Sampson says it is ice that creates the biggest risk for workouts outside when it is very cold. People don't see the ice, step on it and fall.
But if you are dressed right, you can exercise safely in low temperatures.
Experts on several health websites say it is important to dress in layers.
The layer closest to the body should be made of a material that takes moisture away from the body. The next layer should be a material that traps heat, such as wool. And finally, the outer layer should be water resistant.
Of course, don't forget gloves, hat, good socks and shoes. When it is really cold, a scarf or face mask will protect your skin and lungs.
Check the weather forecast
Temperature is not the only things that will affect your outdoor workout. It is also important to consider wind and water.
Wind can go through your clothing and steal the layer of warm air that surrounds your body. If you get wet, you may not be able to keep your body temperature high enough.
So, if you are a generally healthy person, do not think you must move your workouts indoors in winter. As long as you dress properly, drink enough water and exercise safely, you can get a lot out of a cold-weather workout.
And that's the Health & Lifestyle Report.
I'm Anna Matteo.
1.at least 至少
He had been sitting on the document for at least two months.
2.As long as 只要
As long as I deliver the goods, my boss is very happy.
3.body temperature 体温
Body temperature can fluctuate if you are ill.
4.go through 穿过
The bill might have gone through if the economy was growing.
5.With frostbite people can start experiencing symptoms pretty rapidly, on average with mild winds and cold temperatures it can occur in as less than 30 minutes, with extreme cases.
on average 平均；通常
American shares rose, on average, by 38%
On average each report requires 1,000 hours to prepare.
6.Exercising outdoors in cold weather may help your mental health.
mental health 心理健康
The college student's self-identity is the important factor to influence college student's mental health.
Mental health is determined by socio-economic, biological and environmental factors.
在冬季，人们会尽量减少户外运动 。白昼时间逐渐缩短，天气寒冷 。这些条件导致一些人到户外锻炼的难度加大 。
南卡罗来纳医科大学的健康专家们称，在低温状态下，人体需要产生多余的热量维持体温 。这意味着身体会燃烧更多卡路里和脂肪 。
在寒冷天气下，肺部功能会有所提升 。弗拉格斯塔夫市北亚利桑那大学的研究人员在关于山羊的研究中发现一些有趣的结果 。
科学家研究了寒冷天气对山羊的影响 。他们发现，“在最寒冷的三个月里，暴露在严寒中但久坐不动的山羊，其最大摄氧量增加了34%，其奔跑速度提升了29% 。”当春季气温上升时，山羊的摄氧量和奔跑速度都会下降 。
冬季还是感冒和流感的高发季节 。将户外运动纳入锻炼日程能够帮助人们抵御感冒和流感侵袭 。它可以增强人体免疫系统 。
户外锻炼能够多晒太阳 。阳光有助于身体分泌维生素D，而维生素D会产生让你心情愉悦的激素 。
爱德华·沃德（Edward Ward）是拉什大学医学中心的医生 。他详述了冻伤的产生过程 。
他说：“当气温跌破零度，尤其是加上风寒，冻伤的情况就会出现，包括手指、脚趾、鼻子、耳朵等等 。任何暴露在风寒中的物体都可能受到冻伤影响 。”
手指、脚趾、耳朵和鼻子的保暖工作非常重要 。人体的这些部位会最先受到寒风的伤害 。
克里斯托弗·桑普森（Christopher Sampson）是密苏里州大学卫生保健部的医生 。他解释说，不到30分钟可能就会出现冻伤 。
他说：“冻伤患者很快会出现症状 。在弱风和低温下，冻伤一般不到30分钟内发生 。而在极寒天气下，再加上强烈的寒风，有时短短5分钟内就能导致冻伤 。”
梅奥诊所的专家指出，“轻微冻伤会使皮肤发红，并且感觉寒冷 。继续暴露的话，该部位会出现刺痛和麻木 。皮肤转暖后可能会产生疼痛和刺痛感 。亚冻伤不会给皮肤造成永久性伤害 。”
冻伤则不然 。冻伤会造成部分组织和四肢失去知觉 。
最严重的危害是失温 。失温是指体温降至35摄氏度（或95华氏度）以下 。当身体无法产生充足热量维持体温时会发生这种现象 。
然而，桑普森博士指出，天气寒冷时进行户外锻炼的最大的隐患是冰 。人们没注意到冰，容易滑倒 。
贴身衣物应首选吸汗布料 。第二层应该选用保暖性衣物，例如羊毛 。最外层应该选择防水性衣物 。
当然，不要忘记手套、帽子、保暖袜和鞋子 。遇到严寒天气，戴上围巾和口罩可以保护皮肤和肺部 。
温度不是影响户外锻炼的唯一因素 。刮风和下雨也要纳入考虑范围 。
风可以穿透衣物，刮走身体周围的热量 。如果衣物潮湿，你可能无法维持足够高的体温 。
因此，如果你身体康健，不要觉得冬季必须要在室内锻炼 。只要你穿着得当，饮水充足，并安全地锻炼，你就能从寒冷天气的锻炼中受益良多 。